CVE-2011-1547 in NetBSD
Summary
by MITRE
Multiple stack consumption vulnerabilities in the kernel in NetBSD 4.0, 5.0 before 5.0.3, and 5.1 before 5.1.1, when IPsec is enabled, allow remote attackers to cause a denial of service (memory corruption and panic) or possibly have unspecified other impact via a crafted (1) IPv4 or (2) IPv6 packet with nested IPComp headers.
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Analysis
by VulDB Data Team • 08/04/2024
The vulnerability identified as CVE-2011-1547 represents a critical stack consumption flaw affecting NetBSD operating systems across multiple versions including 4.0, 5.0 before 5.0.3, and 5.1 before 5.1.1. This vulnerability specifically targets the kernel's handling of IPsec traffic when IPComp compression is enabled, creating a pathway for remote attackers to exploit memory corruption issues that can result in system crashes or potentially more severe consequences. The flaw manifests through crafted IPv4 or IPv6 packets containing nested IPComp headers, which when processed by the vulnerable kernel can trigger stack overflow conditions that lead to system instability.
The technical nature of this vulnerability stems from insufficient validation of nested IPComp headers within the IPsec processing pipeline of the NetBSD kernel. When the kernel encounters these malformed packets, it fails to properly handle the recursive header structures, leading to excessive stack consumption that can cause memory corruption. This type of vulnerability falls under CWE-121, which describes stack-based buffer overflow conditions, and represents a classic example of improper input validation in kernel space code. The exploitation mechanism relies on the kernel's inability to properly parse and validate nested compression headers, which can cause the stack to grow beyond its allocated boundaries during packet processing operations.
The operational impact of CVE-2011-1547 extends beyond simple denial of service scenarios, as the vulnerability can potentially lead to system panics and memory corruption that may be exploited for more sophisticated attacks. Remote attackers can leverage this vulnerability to disrupt network services by sending carefully crafted packets that trigger kernel memory corruption, resulting in system crashes that can affect availability of critical network infrastructure. The vulnerability affects systems running IPsec with IPComp enabled, which is commonly used in secure network communications, making it particularly dangerous for enterprise environments that rely on such security protocols. The potential for unspecified other impacts suggests that under certain conditions, this vulnerability could be exploitable for privilege escalation or information disclosure, though the primary risk remains denial of service and system instability.
Mitigation strategies for CVE-2011-1547 should focus on immediate system updates to patched versions of NetBSD, specifically versions 5.0.3 and 5.1.1 or later, which contain the necessary kernel fixes to properly validate nested IPComp headers. System administrators should also consider disabling IPComp compression in IPsec configurations when the vulnerability cannot be immediately addressed through patching, as this removes the attack vector entirely. Network segmentation and firewall rules can be implemented to filter out suspicious packets containing nested IPComp headers, though this approach provides only partial protection. Additionally, monitoring for unusual network traffic patterns and system crashes can help detect exploitation attempts, while implementing proper intrusion detection systems can provide early warning of potential attacks targeting this vulnerability. The ATT&CK framework categorizes this vulnerability under privilege escalation and denial of service tactics, with the exploitation requiring remote network access and targeting kernel-level memory management functions. Organizations should also consider implementing network-based intrusion prevention systems that can detect and block malformed IP packets containing nested compression headers, as these systems provide an additional layer of defense against exploitation attempts.